Strongly Enhanced Thermal Stability of Crystalline Organic Thin Films Induced by Aluminum Oxide Capping Layers

TL;DR

This study demonstrates that aluminum oxide capping layers significantly improve the thermal stability of organic thin films, allowing them to remain crystalline at temperatures much higher than uncapped films, due to weak diffusion and well-defined interfaces.

Contribution

The paper introduces a method to enhance the thermal stability of organic thin films using aluminum oxide capping layers, showing a substantial increase in temperature resilience.

Findings

Organic films remain crystalline up to 460°C with aluminum oxide capping.

Thermal stability is significantly higher than uncapped or metal-capped films.

Weak diffusion and well-defined interfaces are key to stability.

Abstract

We show that the thermal stability of thin films of the organic semiconductor diindenoperylene (DIP) can be strongly enhanced by aluminum oxide capping layers. By thermal desorption spectroscopy and in-situ X-ray diffraction we demonstrate that organic films do not only stay on the substrate, but even remain crystalline up to 460C, i.e. 270 deg. above their desorption point for uncapped films (190C). We argue that this strong enhancement of the thermal stability compared to uncapped and also metal-capped organic layers is related to the very weak diffusion of aluminum oxide and the structurally well-defined as-grown interfaces. We discuss possible mechanisms for the eventual breakdown at high temperatures.